The question is can a math teacher be replaced by a video presentation or even a computer application. Most teachers would instantly jump to the answer no way! Well I would give a qualified agreement with the teachers on that. There is no computer program in the world or video class that can do everything that a math teacher does and has to deal with. But saying that let us look at what it can be achieved with modern computer programs and video software.
Video is only ever going to be a reproduction of what a teacher has done and is really only one-way interaction enabled. No good asking a video questions if you need clarification on a point. But consider a student who has a unmotivated and bored teacher (come on we've all had them in our time) they might actually be much better off with a video and the textbook. The big advantage of a video over a teacher is that the student is now in control. The student can pause it, try something out replay it and rewind to review parts if they want. The student can learn the topic at their own pace. This is the biggest problem of classroom teaching, students as we all know don't learn at the same pace and a teacher is forced to cater for the lowest common denominator, resulting in a number of bored students.
Teachers should have nothing to fear from video and applications that enable student to self learn. The job of a teacher is to enable students to improve and access the concepts and information they need. They should have no fear for a third party be it tutor, video or application that is helping a student to achieve in math. You could even go as far and say to a teacher in reality to do their job right they should introduce these for use at home, both video and web based applications to improve math because in this way they are giving the kids the information and a choice of avenues to learning the subject matter at hand.
There are now fantastic services available on the web for getting video presentations of different topics and they really are a boon to modern day students in getting in touch with math enabling them to learn at their own pace. If I was a teacher I wouldn't worry about arriving at work and seeing a big 52" screen where my desk used to be or Robbie the robot because who would there be for the students to complain about?